The present invention relates to the field of data transmission through any desired medium, in particular binary signals within a band-limited radio channel, and more particularly to a method for transmitting a data word containing a sequence of individual data in sequential data positions.
The ever expanding fields of application for data transmission and increasing volumes of data to be transmitted create an increasing need for transmission methods which enable data to be transmitted at a high rate and at a low data error rate, i.e., in a manner that is highly tolerant of data transmission errors, using simple and economical means.
The important parameters that characterize the performance of present-day transmission methods are the transmission of bit/s per Hz bandwidth of the channel (channel-specific data rate) and the level of interference immunity.
Against this background, it proceeds from the realization proposal relating to the IEEE standard 802.15.4 (low-rate wireless personal area network) “PHY Proposal for the Low Rate 802.15.4 Standard” by Ed Callaway, Motorola Labs, (http://grouper.ieee.org/groups/802/15/index.html) to use sequences (code words) which are generated by the cyclical shifting of a pseudo-noise basic word. According to this proposal, a 4-bit data word is assigned to each code word. Following transmission of the code word, the original 4-bit data word can be identified from the phase position of the maximum of the correlation function by making a correlation with a code reference.
However, this method is characterized by a relatively limited performance, particularly with regard to the data rate.
A method for transmitting a data word is described in a paper by Letaief et al. (“Multicode High-Speed Transmission for Wireless Mobile Communications”; IEEE, GLOBECOM 1995, Nov. 13-17, 1995, vol. 3, pp. 1835-1839), in which an incoming data word is serial-to-parallel converted into a plurality of parallel bit data streams. For each data stream of a specific data position, the particular binary datum is linked to an individually assigned code word (“signature sequence”) and subsequently carrier modulated. The modulated signals of all bit data streams are then transmitted in parallel to a receiver and appear there as summed signals. As far as the properties of the code words is concerned, it is merely elaborated that PN sequences are traditionally used in multiple access information technology. This method entails relatively substantial outlay and is limited, particularly with regard to the modulation carrier.
The paper by Huang, X; Li, Y. “The Multicode Interleaved DSSS System for High-Speed Wireless Digital Communications” (IEEE, ICC 2001, Jun. 11-14, 2001, vol. 10, pp. 2990-2994) discusses the possibility of using cyclically shifted m-sequences as code words.